Vacuum substrate processing system having multiple processing chambers and a central load/unload chamber

ABSTRACT

The present invention includes plural plasma processing vessels and a wafer queuing station arrayed with a wafer transfer arm in a controlled environment. Wafers are movable within the controlled environment one at a time selectably between the several plasma vessels and the wafer queuing station without atmospheric or other exposure so that possible contamination of the moved wafers is prevented. The system is selectively operative in either single-step or multiple-step processing modes, and in either of the modes, the several plasma etching vessels are operable to provide a desirably high system throughput. In the preferred embodiment, the several plasma vessels and the queuing station are arrayed about a closed pentagonal locus with the wafer transfer arm disposed within the closed locus. The wafer transfer arm is movable in R and Θ between the several plasma etching vessels and the wafer queuing station, and selectably actuatable vacuum locks are provided between each of the plasma etching vessels and the R and Θ movable wafer transfer arm to both maintain an intended atmospheric condition and to allow wafer transport therethrough. The plasma vessels each include first and second water-cooled electrodes that are movable relatively to each other so as to provide a selectable gap dimension therebetween. One of the electrodes includes a selectively movable pedestal portion slidably mounted thereto that is cooperative with the R and Θ movable wafer transfer arm to load and unload wafers respectively into and out of the associated plasma vessel. The wafer transfer arm is operative to pick-up the wafers by back-side and peripheral wafer contact only, which therewith prevents possible front-side contact-induced contamination of the wafer surfaces. A sensor on the transfer arm is operative to provide a signal indication of proper wafer seating.

RELATED APPLICATION

This application is a divisional of Ser. No. 08/453,060, filed May 26,1995, which is a continuation of Ser. No. 08/276,218, filed Jul. 15,1994, now abandoned which is a continuation of Ser. No. 07/809,031,filed Dec. 16, 1996 and now issued as U.S. Pat. No. 5,344,542, which isa continuation of Ser. No. 07/456,036, filed Dec. 22, 1989, nowabandoned which is a continuation of Ser. No. 06/853,775, filed Apr. 18,1986 now abandoned.

FIELD OF THE INVENTION

This invention is directed to the field of semiconductor processing, andmore particularly, to a novel multiple-processing and contamination-freeplasma etching system.

BACKGROUND OF THE INVENTION

Plasma processing devices are commonly employed during one or more ofthe phases of the integrated circuit fabrication process, and aretypically available in either a single-wafer or a plural-waferconfiguration. The single-wafer configurations, while providingexcellent process control, suffer from a restricted system throughputcapability. Efforts to relieve the throughput limitations, such as thosethat have employed faster but higher-temperature processes, have beengenerally unsuccessful. For these higher-temperature processingprocesses, system utility is limited due to the undesirable phenomenonof resist “popping”, notwithstanding that various cooling approacheshave been used including clamping, cooling of the wafer underside with ahelium flow, and the mixing of helium into the plasma. Themultiple-wafer configurations, while providing a comparativelymuch-greater system throughput, have been generally subject toless-than-desirable process and quality control. Not only are end-pointdeterminations for each of the multiple wafers either not available ornot precisely determinable, but also electrode positional accuracy fordifferent electrode gaps and correspondingly different gas chemistriesis often difficult to establish and maintain. The single-wafer and themultiple-wafer configurations are both subject to the furtherdisadvantage that two or more step processes typically expose the wafersto an undesirable environment in the intermediate handling step, whichmaterially increases the possibility of wafer contamination, and whichfurther restricts the processing throughput.

SUMMARY OF THE INVENTION

The present invention contemplates plural single-wafer plasma reactorseach operative individually to provide excellent process control ofsingle wafers, collectively operative to provide a system throughputlimited only by the number of the plural plasma reactors, and socooperative with a common wafer transfer and queuing means as to provideboth single-step and multiple-step wafer processing in a manner thatneither exposes the wafers to an undesirable atmosphere nor to humanhandling.

In the preferred embodiment, plural plasma reactors and a cassetteelevator are symmetrically arrayed about an X, Θ movable wafer armassembly. The plural reactors, the cassette elevator, and the X, Θmovable wafer arm are maintained in a controlled vacuum condition, andthe central X, Θ movable wafer arm is in radial communication with theperipherally surrounding plasma reactors and cassette elevator via acorresponding one of a plurality of vacuum lock valves. The arm of theR, Θ movable wafer arm assembly includes an apertured platform forsupporting each wafer, and a cooperative bumper for releasably engagingthe back and the periphery of the supported wafer without any waferfront surface contact. Plural wafer contact responsive sensors mountedto the platform are operative to provide a signal indication of whetheror not the wafer is in a properly seated condition. Each of the pluralplasma reactors includes a stationary bottom electrode and a movableupper electrode that are cooperative to provide a variable wafer-cathodeto anode gap therebetween of a selectable dimension. In one embodiment,a support assembly including a micrometer adjustment stop is providedfor selectively positioning the movable electrode, and in anotherembodiment, a combination micrometer stop and pneumatic actuators areprovided for selectively positioning the movable electrode. A verticallymovable pedestal is slidably mounted centrally to the stationaryelectrode of each of the plural plasma reactors that cooperates with theapertured platform of the R, Θ movable wafer arm assembly to load andunload the wafers respectively onto and off of the stationary electrode.A reactant gas injection system, a RF power source, and an end-pointdetermination means are operatively coupled to each of the plural plasmareactors. The plural plasma reactors are operable in either embodimentto run the same or different processes, and are cooperative with the R,Θ movable wafer arm assembly to provide one of the same single-stepprocessing simultaneously in the plural plasma reactors, differentsingle-step processing simultaneously in the plural plasma reactors, andsequential two or more step processing in the plural reactors. Twoembodiments of the R, Θ movable wafer arm assembly are disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, and advantages, of the present invention willbecome apparent as the invention becomes better understood by referringto the following solely-exemplary and non-limiting detailed descriptionof the preferred embodiments thereof, and to the drawings, wherein:

FIG. 1 is a pictorial diagram illustrating the multiple-processing andcontamination-free plasma processing system according to the presentinvention;

FIG. 2 is a fragmentary plan view, partially broken away, of themultiple-processing and contamination-free plasma etching systemaccording to the present invention;

FIG. 3 illustrates in FIG. 3A and in FIG. 3B partially schematic sideand end elevational views respectively illustrating the vacuum locksintermediate a corresponding plasma reactor and the R, Θ movable armassembly of the multiple-processing and contamination-free plasmaetching system according to the present invention;

FIG. 4 is a partially pictorial and partially sectional view useful inexplaining the operation of the R, Θ movable wafer arm assembly of themultiple-processing and contamination-free plasma etching systemaccording to the present invention;

FIG. 5 is a perspective view of a first embodiment of the R, Θ movablewafer arm assembly of the multiple-processing and contamination-freeplasma etching system according to the present invention;

FIGS. 6 and 7 are plan views of the first embodiment of the R, Θ movablewafer arm assembly illustrating different movement positions of the R, Θmovable wafer arm assembly of the multiple-processing andcontamination-free plasma etching system of the present invention;

FIG. 8 is a partially broken-away and fragmentary isometric viewillustrating a portion of the first embodiment of the R, Θ movable armassembly of the multiple-processing and contamination-free plasmaetching system of the present invention;

FIG. 9 is a partially pictorial and partially schematic side viewillustrating a plasma reactor of the multiple-processing andcontamination-free plasma etching system according to the presentinvention;

FIG. 10 is diagramatic view illustrating the several reactant injectionsystems and controlled vacuum system of the multiple-processing andcontamination-free plasma etching system of the present invention;

FIG. 11A is a perspective view and FIG. 11B is a sectional view of asecond embodiment of the R, Θ movable arm assembly of themultiple-processing and contamination-free plasma etching system of thepresent invention;

FIG. 12 is a perspective view of a portion of the second embodiment ofthe R, Θ movable wafer arm assembly of the multiple-processing andcontamination-free plasma etching system according to the presentinvention; and

FIGS. 13-18 are SEM micrographs illustrating exemplary microstructuresobtainable by the multiple-processing and contamination free plasmaetching system according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1, generally designated at 10 is a pictorialdiagram illustrating the multiple-processing and contamination-freeplasma etching system according to the present invention. The system 10includes a plurality of single-wafer plasma reactors generallydesignated 12 to be described and a wafer queuing station generallydesignated 14 to be described that are arrayed about a closed locus asillustrated by a dashed line 16. A load/unload module generallydesignated 18 to be described is disposed concentrically within theplural plasma reactors 12 and the queuing station 14 for singlytransferring wafers to be processed and after processing between thequeuing station 14 and one or more of the plasma reactors 12. Aplurality of vacuum locks generally designated 20 to be described areindividually provided at the interfaces of the several plasma reactors12 and the load and unload module 18, and between the interface of thequeuing station 14 and the load and unload module 18. A processor 22 isoperatively coupled to the plural plasma reactors 12, to the queuingstation 14, and to the load and unload module 18 for activating andde-energizing radio frequency plasma inducing fields in well-knownmanner, for controlling and processing in well-known manner the signaloutput of end-point determination means coupled to the several plasmareactors, and for initiating and coordinating wafer transfer between theseveral reactors and the queuing station to be described.

A reactant gas injection system 24 to be described is operativelycoupled to the plural plasma reactors 12 for controllably injectingpreselected reactants and other process gases severally into the pluralplasma reactors. A vacuum system 26 is operatively coupled to thereactors 12, to the queuing station 14, and to the load and unloadmodule 18 for maintaining the entire assembly at a controlled vacuumcondition during operation. The processor 22 is operatively coupled tothe reactant gas injection system and to the vacuum system 26.

The several reactors 12, the queuing station 14, and the concentric loadand unload module 18 conserve space utilization and in such a way as toprovide a comparatively-compact plasma etching system. The load andunload module 18 and cooperative ones of the vacuum locks 20 areoperable to transfer wafers singly between the queuing station 14 andselected reactors 12 in a single-step processing mode and betweenselected reactors 12 in a two or more step processing mode without anyresidual or environmentally-induced wafer contamination as well aswithout intermediate operator handling. Among other additionaladvantages, the plasma etching system of the present invention ischaracterized by both an excellent process control and a high processingthroughput, the mutual co-existence of both features having notheretofore been possible in a practicable embodiment.

Referring now to FIG. 2, generally designated at 30 is a fragmentaryplan view, partially broken-away, illustrating the multiple-processingand contamination-free plasma etching system of the present invention.The queuing station 14 preferably includes a cassette, not shown, havingplural vertically-spaced wafers 32 stacked therein. The cassette ispreferably mounted for vertical stepping motion by an indexed elevatorassembly schematically illustrated at 34, that is operable under controlof the processor 22 (FIG. 1) to step the cassette in vertical incrementsthat correspond to the spacing of the vertically spaced wafers foraddressing the associated cassette slot position. It will be appreciatedthat in this way individual wafers in the cassette are addressed forremoval for processing and for return after processing to theircorresponding slot positions. It should be noted that although acassette and indexed elevator assembly are presently preferred, anyother suitable wafer queuing station can be employed as well withoutdeparting from the inventive concept.

Referring now to FIGS. 2, 3A and 3B, the vacuum locks 20 intermediatethe queuing station 14 and the load/unload module 18 and intermediatethe plural plasma reactors 12 and the load and unload station 18 eachinclude a housing body generally designated 40. The housing 40 includesa plate 42 having opposing top, bottom, and side walls 44 orthogonalthereto that cooperate to define a generally-rectangular hollowgenerally designated 46 therewithin as best seen in FIG. 3A. A flange 47is provided peripherally around the walls 44 on the ends thereof remotefrom the plate 42, and bolts 48 are provided through the ends of theplate 42 and of the flange 47 for fastening the housing body 40 at theinterfaces between corresponding ones of the plasma reactors 12 and theload and unload station 18 and between the interface between the queuingstation 14 and the load and unload station 18. O-rings 50 are providedon the sealing faces of the plate 42 and flange 47 for providing anair-tight seal. An elongated slot generally designated 54 is providedthrough the plate 47 that is in communication with thegenerally-rectangular hollow 46.

A chamber door assembly generally designated 56 is cooperative with theslot 54 to provide a valving action. The door assembly 56 includes anelongated, generally-rectangular plate 58 of dimensions selected to belarger than the dimensions of the slot 54. An O-ring sealing member 60is provided in the sealing face of the plate 58 and surrounding the slot54. The plate 58 is fastened to an arm 62 that is mounted for rotarymotion with a shaft 64 journaled in spaced bearings 66 that are fastenedto the plate 42. A chamber door Θ-drive actuator, not shown, is fastenedto the shaft 64 through an edge of the housing 40 preferably via aferrofluidic or other rotary seal as illustrated dashed at 70.

The chamber door 56 is pivoted by the chamber door Θ-drive actuatorbetween an open condition, illustrated in dashed outline in FIG. 3A, anda closed condition, illustrated in solid outline in FIGS. 3A and 3B. Inits open condition, the generally rectangular hollow 46 is in opencommunication with the elongated slot 54, so that a wafer arm assemblyto be described may readily be moved therethrough between the load andunload station 18 and the several plasma reactors 12 and queuing station14. In the closed condition of the door assembly 56, the load and unloadmodule is sealed from the plural plasma reactors 12 and from the queuingstation 14.

Referring now to FIGS. 2 and 4, the load and unload module 18 includes atop wall 72, pentagonally-arranged side walls 74, and a pentagonalbottom wall 76 defining an enclosure generally designated 78. A R, Θmovable wafer arm assembly generally designated 80 to be described ismounted in the enclosure 78. The assembly 80 includes a turntable 82mounted for Θ-rotation with a shaft 84 journaled in a bearing assemblygenerally designated 86 that is fastened in a central aperture providedtherefor in the bottom wall 76. A Θ drive motor 88 mounted to the bottomwall 76 is operatively coupled to the shaft 84 via a belt and wheelarrangement generally designated 90. With controlled rotation of theshaft of the Θ-motor 88, the shaft 84 and therewith the turntable 82rotates to any selected angular Θ orientation for aligning the wafer armassembly 80 with any one of the plasma reactors 12 or with the queuingstation 14 at the corresponding Θ₁, Θ₂, Θ₃, Θ₄, and Θ₅ coordinates.

A shaft 92 is concentrically mounted within the shaft 84 and journaledfor rotation therein on a bearing and vacuum seal assembly generallydesignated 93. Any suitable rotary vacuum seal, such as a ferrofluidicrotary vacuum seal, may be employed. One end of the shaft 92 isconnected to a pivot bearing 94 to be described vacuum-mounted throughthe turntable 82, and the other end of the shaft 92 is operativelycoupled to a R-drive motor 96 via a belt and wheel arrangement generallydesignated 98. As described more fully below, with the controlledrotation of the shaft of the R-drive motor 96, the wafer arm of bothembodiments of the R, Θ movable wafer arm assembly to be described iscontrollably translated in the R-direction for loading and unloadingindividual wafers into and out of the plural reaction chambers 12 andqueuing station 14 through the associated vacuum lock 20.

Referring now to FIGS. 2, 4, and 5, the wafer arm assembly 80 includes awafer receiving and releasing paddle assembly generally designated 100.The paddle assembly 100 includes a platform 102 having a central openinggenerally designated 104 therethrough. The member 102 terminates inlaterally spaced fingers 106 having wafer-periphery engaging upstandingflanges 108 integrally formed on the free ends thereof. A releasableabutment generally designated 110 having a bumper portion 112 and anintegral tail portion 114 is mounted for sliding motion to the platformmember 102. As best seen in FIG. 8, a coil spring 116 is mounted betweenthe releasable abutment 110 and the member 102 which urges the bumper112 in the direction of an arrow 118 so as to abut and therewithfrictionally engage the periphery of a wafer, not shown, receivedbetween the bumper 112 and the flanges 108. The tail 114 includes adownwardly depending stop 120 to be described that is slidably receivedin an elongated aperture provided therefor in the platform member 102that is cooperative with an upstanding abutment to be described torelease the frictional wafer engagement as the arm reaches its positionof maximum extension. The paddle assembly 100 is mounted between plates124 to a carriage assembly generally designated 126 that is slidablymounted on linear bearings 128 that are fastened to end posts 130upstanding from and fastened to the rotatable turntable 82.

The carriage 126 is controllably moved in either direction along thelinear bearings 128 for loading and unloading wafers individually to andfrom the several plasma reactors 12 and the queuing station 18. A member131 is pivotally mounted subjacent the carriage 126, which housestherein a linear bearing, not shown. A shaft 132 is slidably receivedthrough the linear bearing of the pivoting housing 131. One end of theshaft 132 is slidably mounted in a sleeve 134 that is mounted for rotarymotion to the turntable 82 via a pivot bearing 136, and the other end ofthe shaft 132 is fastened to a needle bearing assembly 138 that ispivotally fastened to a crank arm 140 mounted for rotation with theshaft 92 of the R-drive motor 96 (FIG. 4) via a mounting coupling 142fastened to the turntable 82.

With controlled rotation of the Θ-drive motor 88, the turntable 82 andtherewith the paddle assembly 100 is rotated to that Θ coordinate thatcorresponds to any selected one of the angular locations of the pluralplasma reaction chambers designated Θ₁ through Θ₄ in FIG. 2, and to thatΘ coordinate that corresponds to the angular location of the waferqueuing station 14 designated Θ₅ in FIG. 2. With the controlled rotationof the R-drive motor 96, the crank 140 races an arcuate path asillustrated by an arrow 144. The arm 132 therewith pivots on the pivotbearing 136 as shown by an arrow 146, and moves the carriage 126linearly along the bearings 128 in a direction that corresponds to thesense of rotation of the X-drive motor as illustrated by an arrow 148.The arm is either more or less elongated relative to the coupling 136 asit is pivoted by the crank 140, and depending on the sense of therotation, it slides within the sleeve 134 and within the housing 131 asillustrated by an arrow 150. When the crank 140 is turned to its maximumclockwise position, the paddle assembly 100 moves into its fullyretracted position as illustrated generally at 152 in FIG. 6. Withcounterclockwise motion of the crank arm 140 the paddle moves along theR direction as illustrated generally at 154 in FIG. 7. As the paddleassembly 100 nears its fully extended position, close to the maximumallowed counterclockwise rotation of the R-drive motor, the stop 120 onthe tail portion 110 abuts the confronting wall of the upstanding endpost 130, such that with continued motion of the paddle along the Rdirection the bumper 110 draws away from the flanges 108 and therebyreleases the frictional engagement of the wafer periphery. In themaximum extended position, then, the wafers are free to be loaded orunloaded to and from any selected plasma reactor 12 and/or are free forpick up or delivery back into the queuing station 14.

Contacts 156, preferably three in number, are mounted to the platformmember 102 of the paddle assembly 100 as shown in FIG. 7. The contactsare operative in response to the presence of a supported wafer toprovide a three-point signal indicative of whether or not the wafer isproperly seated on the wafer transfer arm. The contacts preferably areformed on a printed circuit board, not shown, mounted to the paddleassembly 100. A different number thereof, or other sensing means may beutilized so long as an accurate indication of intended seating ofindividual wafers is provided.

Referring now to FIG. 9, generally designated at 160 is a partiallypictorial and partially schematic side view illustrating a plasmareactor of the multiple-processing and contamination-free plasma etchingsystem according to the present invention. Each of the plasma reactors160 includes a top plate 162, a spaced-apart bottom plate 164 and acylindrical sidewall 166 cooperate to define a plasma chamber generallydesignated 168. A first electrode generally designated 170 is fastenedto the bottom plate 164. A pedestal schematically illustrated dashed at172 is slidably mounted centrally in the bottom electrode 170 forvertical motion with the shaft of a pnuematic cylinder schematicallyillustrated in dashed outline 174. As described more fully below, thepedestal 172 is cooperative with the paddle arm assembly to allow forremoval and delivery of individual wafers into and out of the plasmachambers. The pedestal pnuematic cylinder 174 is driven by a controlledair supply, not shown, operatively coupled thereto via an air input port176 and an air output port 178. As illustrated by dashed outline 180, asource of cooling liquid, not shown, is coupled to internal fluid flowpassageways, not shown, provided through the interior of the bottomelectrode 170 via input and output ports 182, 184 for removing the heatproduced in the bottom electrode during plasma etching.

A top electrode generally designated 186 is fastened to a support shaftgenerally designated 188 that is slidably received through the top plate162 in a vacuum-tight sealing engagement therewith as by a stainlesssteel vacuum bellows 190 fastened between the top plate 162 and asuperadjacent shaft support plate 187. The top electrode 186 includesinternal cooling/heating fluid flow passageways schematicallyillustrated in dashed outline 189 that are coupled via fluid flowconduits 190 disposed in the shaft 188 to a source, not shown, via aliquid input port 194 and an output port 196 provided in the plateassembly 187. A pneumatic actuator generally designated 200 having a ram202 is mounted to the support plate assembly 187. With the ram 202 inits extended position, not shown, the plate 187 moves upwardly, andtherewith the shaft 188 and electrode 186 move upwardly and away fromthe stationary bottom electrode 170. With the ram lowered as shown,micrometer adjustment posts 204 fastened to the plate assembly 187 bearagainst the top plate 162 and therewith support the top electrode 186 inan intended spaced-apart relation with the bottom electrode 170. The gapbetween the electrodes is adjustable by changing the length of themicrometer adjustment posts selectively. In the preferred embodiment,between {fraction (3/16)} inch (5 mm) to 2 inches (50 mm) of gapadjustment is provided.

The shaft 188 has a hollow interior generally designated 206, and alaser window 208 is mounted across the hollow of the shaft 206. The beamof an external laser, not shown, passes through the window and hollowshaft for providing end-point determinations of the plasma etch state.Other end-point determination means, such as a lateral optical detector,may be employed as well without departing from the inventive concept.Reactant gas injection ports 210 are coupled via internal shaft conduitsprovided therefor, not shown, to a liquid-cooled showerhead gas manifoldillustrated in dashed outline 211 in the upper electrode 186. Reactantgas is controllably released therefrom into the plasma reactor, andradio frequency power is applied in the plasma reaction chambers. In analternative embodiment, the spacing between the electrodes can bepreselected for each particular plasma process, and additionalmicrometers, in place of the pneumatic actuators 200, can advantageouslybe employed.

Referring now to FIG. 10, generally designated at 212 is a schematicdiagram illustrating the presently preferred gas injection andcontrolled vacuum systems. Preferably, four independently valved sourcesof gases are respectively connected to individual ones of the plasmavessels via corresponding ones of a plurality of gas manifolds, twobanks of gas sources generally designated 214, 216 and two manifolds218, 220 being specifically illustrated. A vacuum system 222 isoperatively coupled in common to the plural plasma reactor chambers, tothe queuing station 224, and to the load and unload island 226. Thevacuum system controls the vacuum condition in the entire system, sothat the wafers are free from possible contamination as the vacuum locksare severally opened and closed during single and multiple phaseprocessing wafer transfer. It should be noted that while four plasmareactors are disclosed, a greater or a lesser number can be employedwithout departing from the inventive concept.

Referring now to FIG. 11A, generally designated at 230 is a perspectiveview of an alternative embodiment of the X, Θ wafer arm assemblyaccording to the present invention. The assembly 230 includes a pulley232 mounted for rotation with the shaft of the Θ drive motor as bestseen in FIG. 11B. The pulley 232 includes a grooved rim 234 around whicha cable 236 is wrapped. The cable is drawn tangentally to the groovedrib 234 in opposing directions, and respectively wrapped over pulleys238, 240 and tied to a slide 242, as best seen at 244 in FIG. 11B. Withthe angular rotation of the pulley 232, the slide 242 linearly movesalong the the linear bearings 246. A wafer arm generally designated 248is mounted for movement with the slide 242 such that the arm 248 iscontrollably extended and retracted in dependence on the angularposition of the pulley 232. To provide constant tension in the cable236, the ends of the cable preferably are terminated in the slide 242against resilient biasing elements generally designated 250 in FIG. 12.The cable 236 as it stretches is pulled in a reverse direction by theresilient couplings 250 for maintaining its intended state.

During the plasma chamber load cycles, the Θ-drive motor turns theturntable of the R, Θ wafer arm assembly to the Θ coordinate of thequeuing station in either embodiment of the R, Θ movable wafer armassembly. The vacuum lock of the associated interface is released, andthe arm is extended under the wafer in the addressed cassette slotposition. The arm is then retracted back into the load and unloadmodule, and the vacuum lock is restored. The R, Θ wafer arm assembly isthen rotated to the Θ coordinate of the selected plasma reactor. Theassociated chamber door is then rotated to its open condition forproviding access to the selected reaction chamber, and the upperelectrode is raised. The wafer receiving arm is then extended in the Rdirection through the associated slot valve opening and into theselected reaction chamber. As it approaches the limit of its maximumradial travel, the depending stop flange on the wafer arm abuts theupstanding end post on the turntable and, with continued radial motion,the bumper withdraws thereby freeing the wafer from peripheral frictionengagement. The central pedestal of the lower electrode is thencontrollably rasied by its pneumatic actuator, and therewith the wafersupported on the arm is elevated upwardly off of the wafer supportplatform. Thereafter, the wafer arm is retracted out of the plasmachamber though the open slot valve and back into the load and unloadstation. The pedestal is then controllably lowered. The wafer lowerstherewith until the pedestal is in its retracted position and the waferis supported on the surface of the lower electrode. The associatedchamber door is then closed, and the upper electrode is lowered to thatprecise preselected gap that implements the particular plasma processbeing run. The intended reactants are then injected through the gasmanifold of the upper electrode, and radio frequency power is applied.Whereupon, plasma etching of each single wafer is continued until thelaser provides a signal indication that the proper end-point has beenachieved. Thereafter, the RF power is turned-off, the vacuum lock isopened, and the above-described process is repeated, but in reverseorder, for removing the wafer out of that plasma chamber and back intothe load and unload station. The wafer can then be moved into anotherplasma reactor for a subsequent process in a two or more step processingmode, or back into the cassette in a one-step processing mode.

The load and unload module, queuing station, and plural reactors areoperable in three basic modes, namely, where each reactor issimultaneously performing the same plasma reaction, where each plasmareactor is simultaneously performing two or more different plasmaprocesses, and where the plasma reactors are severally being operated toprovide multiple-step processing of single wafers before their returnback to the queuing station. In each case, the wafers are transferredand processed in a controlled vacuum environment such that atmosphericexposure and handling induced contamination are wholly eliminated.

FIGS. 13-17 are scanning electron micrographs illustrating exemplarymicrostructures capable of being formed in a single-step process, andFIG. 18 is a scanning electron micrograph illustrating an exemplarymicrostructure capable of being fabricated in a double-step etchprocess. FIG. 13 shows generally at 260 polysilicon with an overlayedphotoresist 262 on the surface of the silicon dioxide layer 264 of thewafer. For exemplary low-resistivity (12-30 ohms) doped polysilicon,CCl₄ at 20 sccn and He at 30 sccm are applied to the plasma reactor at apressure of 100 mt and a power of 300 watts. The etch occurs forapproximately 2½ minutes. As shown in FIG. 14 doped polysilicon 265having a comparatively high resistivity (30-200 ohms per sq.) and havinga slopped profile mask is illustrated. For the illustratedmicrostructure, SF₆ at 50 sccm and Freon 115 (C₂ClF₅) at 50 sccm arecontrollably injected into a plasma reactor at 150 mt pressure and a 100watt power. After about 2½ minutes, the illustrated doped polysiliconmicrostructure is fabricated.

Referring now to FIG. 15, generally designated at 266 is a SEMillustrating an exemplary trench etch. The photoresist is removed, and atrench generally designated 268 is formed in the silicon 272 byinjecting BCl₃ at 5 sccm and Cl₂ at 25 sccm into the plasma reactor at a100 mt chamber pressure and at 750 watts power for about 20 minutes.

Referring now to FIG. 16, refractory silicide, TaSi/poly, is illustratedgenerally at 274. The silicon dioxide surface 276 is overlaid with apolysilicon layer 278 upon which is overlaid the TaSi/poly 280, overwhich overlaid is the photoresist. The microstructure is fabricated byinjecting CCl₄ at 20 sccm and He at 30 sccm into a plasma reactormaintained at a chamber pressure of 80 mt and a radio frequency power of300 watts for about 3½ minutes.

Referring now to FIG. 17, generally designated at 282 is anothermicrostructure exemplary of the single-step structures capable of beingfabricated by the contamination-free and multiple-processing plasmareactor of the present invention. As illustrated, a photoresist 284 islaid over an aluminum and silicon layer 286 which is overlaid via a TiWlayer 288 on the wafer surface. The illustrated structure was fabricatedby injecting BCl₃ at 50 sccm with Cl₂ at 15 sccm into the plasma reactormaintained at 125 mt chamber pressure and a 300 watt RF power for about2½ to 3½ minutes.

Referring now to FIG. 18, generally designated at 290 is a silicondioxide/poly/silicon dioxide/poly sandwich structure illustrating anexemplary two-step process. A poly layer designated poly 1 and an oxidelayer designed oxide are formed after etching with C₂F₆ at 100 sccm at a700 mt pressure and a 600 watt radio frequency power in a first chamber.Thereafter, the upper poly 2 layer and the oxide and an overlaidphotoresist layer are formed by a separate step employing CCl₄ at 20sccm and He at 30 sccm in a second reaction chamber maintained at a 100militore chamber pressure and a 600 watt radio frequency power.

Many modifications of the presently disclosed invention will becomeapparent to those skilled in the art without departing from the scope ofthe appended claims.

What is claimed is:
 1. A multiple-processing contamination-free waferhandling and processing system, comprising: plural, wafer receiving andsurface processing vessels each having a respective ingress and egressdefining port that are arrayed about a predetermined spatial locus insuch a way that the several ports thereof are accessible from a singlelocation spaced from the several ports; a wafer queuing station spacedwith the plural vessels along the same predetermined spatial locusdefining a wafer access port accessible from said single location;plural valves individually coupled to corresponding ones of said plural,vessel ingress and egress ports and to said wafer queuing station waferaccess port; transfer means disposed at said single location andcooperative with corresponding ones of said plural valves for movingwafers from and to said wafer access port of said queuing station fromand to selected ones of said wafer receiving and surface processingvessels through the associated one of said ingress and egress portsthereof; a substantially centrally located wafer support within eachsaid surface processing vessel for supporting wafers transferred to saidvessels by said transfer means; and processor means for controlling saidvessels, said transfer means and said valves to provide selectabilitybetween single-step processing and multi-step processing of wafers insaid queuing station in one or more of said vessels.
 2. The system ofclaim 1, wherein said transfer means includes a wafer arm assemblycontrollably translated through said valves into and out of any of saidprocessing vessels and said queuing station and having a paddle assemblyattached thereto for receiving a wafer on an upper surface thereof andbeing translatable by said wafer arm assembly through said valves. 3.The system of claim 1, wherein said plural processing vessels compriseat least one plasma reactor.
 4. The system of claim 1, furthercomprising a central chamber including said single location, said valvesselectively communicating said central chamber to said plural processingvessels and to said wafer queuing station, wherein said central chambercontains no means for processing said wafers.
 5. A multiple-processingand contamination-free substrate surface processing system, comprising:plural, single-substrate substrate surface processing vessels eachhaving a respective ingress and egress defining port that are arrayedabout a predetermined spatial locus in such a way that the several portsthereof are accessible from a single location spaced from the severalports; a substrate queuing station spaced with the plural vessels alongthe same predetermined spatial locus defining a substrate access portaccessible from said single location; plural valves individually coupledto corresponding ones of said plural, single-substrate substrate surfaceprocessing vessel ingress and egress ports and to said substrate queuingstation substrate access port; single-substrate transfer means disposedat said single location and cooperative with corresponding ones of saidplural valves for moving substrates from and to said substrate accessport of said queuing station from and to selected ones of saidsingle-substrate substrate surface processing vessels through theassociated one of said ingress and egress ports thereof; a substantiallycentrally located substrate support within each said surface processingvessels for supporting one of said substrates on an upper surfacethereof transferred to said upper surface by said transfer means; andprocessor means coupled to said vessels, said transfer means and saidvalves for providing selectability between single-step and multiple-stepsubstrate surface processing of plural substrates, in accordance withcommands, in one or more of said substrate surface processing vessels.6. The system of claim 5, wherein said transfer means includes asubstrate arm assembly controllably translated through said valves intoand out of any of said processing vessels and said queuing station andhaving a paddle assembly attached thereto for receiving one of saidsubstrates on an upper surface thereof and being translatable by saidsubstrate arm assembly through said valves to transfer said onesubstrate from said upper surface of said paddle assembly to said uppersurface of said substrate support.
 7. The system of claim 5, whereinsaid plural processing vessels comprise at least one plasma reactor. 8.The system of claim 5, further comprising a central transfer chamberincluding said single location, said valves selectively communicatingsaid central transfer chamber to said plural processing vessels and tosaid substrate queuing station, wherein said central chamber contains nomeans for processing said substrates.
 9. A multiple-processing andcontamination-free substrate surface processing system, comprising:plural, single-substrate substrate surface processing vessels eachhaving an ingress and egress defining port that are arrayed about apredetermined spatial locus in such a way that the several ports thereofare accessible from a single location spaced from the several ports; asubstrate queuing station spaced with the plural vessels along the samepredetermined spatial locus defining a substrate access port accessiblefrom said single location; plural valve means individually coupled tocorresponding ones of said plural, single-substrate substrate surfaceprocessing vessel ingress and egress ports and to said substrate queuingstation substrate access port; single-substrate transfer means disposedat said single location and cooperative with corresponding ones of saidplural valve means for moving substrates from and to said substrateaccess port of said queuing station from and to selected ones of saidsingle-substrate substrate surface processing vessels through theassociated one of said ingress and egress ports thereof, said transfermeans including a wafer arm assembly controllably translatable throughsaid valve means into and out of any of said processing vessels and saidqueuing station and having a paddle assembly attached thereto forreceiving one of said substrates on an upper surface thereof; and asubstantially centrally located substrate support within each saidsurface processing vessel for supporting on an upper surface thereof oneof said substrates transferred to said upper surface of said substratesupport from said upper surface of said paddle assembly by said transfermeans.
 10. The system of claim 9 further comprising a central chamberincluding said single location, said valves selectively communicatingsaid central chamber to said plural processing vessels and said waferqueuing station, wherein said central chamber contains no means forprocessing wafers.
 11. A substrate processing system, comprising: pluralsingle-substrate substrate surface processing vessels each having aningress and egress defining port that are arrayed about a predeterminedspatial locus; a substrate queuing station spaced with the pluralvessels along the same predetermined spatial locus defining a substrateaccess port; a substrate load/unload module located concentricallywithin said processing vessels and said queuing station; plural valvesindividually coupled to said load/unload module and to correspondingones of said plural vessel ingress and egress ports and said substrateaccess port; a substrate arm assembly located in and rotatable about anaxis within said load/unload module and having a paddle for receiving onan upper surface thereof a substrate and being extensible into any ofsaid processing stations and said queuing station; and a substantiallycentrally located substrate support within each said processing vesselfor supporting on an upper surface thereof one of said substratestransferred to said vessels from said upper surface of said paddle bysaid arm assembly.
 12. The processing system of claim 11, wherein saidprocessing vessels are all plasma reactors.
 13. The system of claim 11wherein said substrate load/unload module includes a chamber havingwalls accommodating said plural valves, wherein said chamber contains nomeans for processing said substrates.